Multidisciplinary expertise from six countries -- France, Germany, Japan, Sweden, the United Kingdom, and the United States -- are pooling resources to examine enduring markers of longevity. The long-term goals of the International Centenarian Study are to (1) compare and contrast characteristics of long-lived individuals from different parts of the world, and (2) identify both culture-free and culture-specific markers of longevity. Specific topics of investigation will embrace eight disciplinary systems, including functional and mental health, genetics, immunology, nutrition and diet, personality, cognition, and support systems.[unreadable]